While Johnson's tenure has been filled with controversial decisions, two flash points erupted back to back in December 2007.

First came the climate-change e-mail incident on Dec. 5.

Then, about two weeks later, came Johnson's big decision on the so-called California waiver - a request by 19 states, including New Jersey and Pennsylvania, for permission to enact stricter tailpipe emission standards.

California sought to reduce car emissions 30 percent by the 2016 model year. EPA had never denied a waiver request from California, but now the auto and oil industries were lobbying the Bush administration to reject it.

An energy bill that included a new but weaker national standard was moving through Congress, and industry lobbyists argued that one national tailpipe standard was better than two.

The EPA career scientists countered that California, given its pollution problems, both natural and man-made, was legally qualified to receive the waiver. In a series of PowerPoint presentations, staff scientists, economists, engineers and lawyers warned Johnson that if the waiver was denied, California was "almost certain" to sue and EPA was "likely to lose."

Senior EPA scientists appealed to Reilly, the former administrator, to lobby Johnson and prepared talking points for him: "You have to find a way to get this done," the talking points read. "If you cannot, you will face a pretty big personal decision about whether you are able to stay in the job. . . ."

Reilly didn't use the talking points, but he did try to persuade Johnson that it was a states-rights issue, and also one of oil independence.

"The argument I received was that Detroit was up against its back to make these changes, but my answer was, 'You have enough time, until 2016, so why not let California drive the system?' " Reilly said. "I don't understand what's wrong with that analysis."

As is his style, Johnson listened to staff presentations and repeatedly asked everyone in the room for an opinion. According to sworn statements to Congress by seven EPA officials, no one at EPA advised Johnson to deny California's request. Handwritten notes by meeting attendees supported this view, congressional investigators said.

"All agreed on granting waiver," scribbled one EPA official.

When Johnson traveled to the White House in early December, aides said, they assumed it was to explain EPA's rationale.

"He went over there with our talking points about granting the waiver," said Burnett, the former deputy associate administrator. Burnett, an heir to a California computer fortune who has contributed $86,000 to Democratic candidates since 2006, added, "When he came back from the meeting, he said he had been reminded of the president's policy preferences."

Johnson rejected California's request, he said, because greenhouse gases contribute to a global and national problem, not one limited to individual states.

EPA had not planned to release the decision immediately, but on Dec. 19 - the same day Bush signed the new energy law that created a national fuel standard - several reporters got wind of it.

Johnson rushed forth an announcement, tying the new energy law to the waiver.

The hurried nature surprised EPA scientists and environmentalists, and drew the ire of two Californians who chair committees that oversee the EPA. They called the decision cowardly. Once again, they said, Johnson had caved to the White House.

The White House called the decision brave.

"It was a classic example of Steve making a decision on the merits for the good of the environment and for the good of the economy - classic," said Connaughton, the senior White House adviser. "Denying the waiver had no environmental consequence, and . . . approving it would have caused massive economic disruption."

Whitman, who resigned from EPA in 2003 over a similar battle with the White House, said, "I think that argument is a little hollow."